1. Field of the Invention
Aspects of the present invention relate to a battery pack. More specifically, aspects of the present invention relate to a battery pack that is specially designed to achieve improved insulation performance and assembly productivity.
2. Description of the Related Art
Compact and lightweight portable electrical/electronic devices, including cellular phones, notebook computers and camcorders, are being actively developed and produced at present. These portable electrical/electronic devices can be operated even in places where no power supply is available because battery packs are embedded therein. Most commercially available battery packs employ secondary batteries capable of repeatedly charging and discharging as they are more economically efficiency. Representative examples of such secondary batteries include nickel-cadmium (Ni—Cd) batteries, nickel-hydrogen (Ni—MH) batteries, lithium batteries, and lithium ion secondary batteries. Of these, the operating voltage of lithium ion secondary batteries is about three times as high as the operating voltages of nickel-cadmium batteries and nickel-hydrogen batteries that are commonly used as power supplies of portable electronic devices. Lithium ion secondary batteries are widely used due to their high energy density per unit weight.
A typical secondary battery uses a lithium oxide as a positive electrode active material and a carbon material as a negative electrode active material. Secondary batteries are generally classified into liquid electrolyte batteries and polymer electrolyte batteries according to the type of electrolytes used in the batteries. The former type batteries are referred to as ‘lithium ion batteries’ and the latter type batteries are referred to as ‘lithium polymer batteries.’
In such a secondary battery, a bare cell is electrically connected to a protective circuit board. The bare cell is produced by accommodating an electrode assembly and an electrolyte in a can and sealing the can. The bare cell is charged and discharged by chemical reactions and the protective circuit board serves to protect the bare cell from overcharge and overdischarge while controlling the charging/discharging of the bare cell.
An auxiliary secondary protective device may be provided in the secondary battery to detect a sudden change in the temperature or voltage of the bare cell and interrupt a flow of current.
The secondary protective device is installed on the upper surface of the bare cell in order to facilitate the detection of a change in the temperature or voltage of the bare cell. In this case, an insulating member is disposed to electrically insulate the secondary protective device from the bare cell.